I got some issues while structuring my database and I would like to know how to solve the below question .
I have a table in database :
id
id_study
writer
1
1
writer1
2
1
writer2
3
2
writer3
Please help me how to combine above 2 table rows to produce output like below :
id
id_study
writer
1,2
1
writer1, writer2
3
2
writer3
SELECT GROUP_CONCAT(id) as id, id_study,GROUP_CONCAT(Writer) as Writer
FROM TABLE
GROUP BY id_study;
Related
I have table where the data is like bellow
Combination_id combination
1 1
1 3
1 4
2 1
2 3
2 5
I want to find the combination_id based on combination.
Test case
1 . For the combination of 1,3,4 I should get combination id 1
2 . For the combination of 1,3,5 I should get combination id 2
I tried many MySQL queries but failed. Can anyone help me here??
Thanks in advance...
There are many ways, but it depends on how your combination is used
For example
select t1.Combination_id
from tab1 t1
where t1.combination in (1,3,4)
group by t1.Combination_id
having count(1) = 3
I have row and column locations of several students.
Assuming number of rows and columns are fixed (to 3x3), how can I have a query result listing all row and column combinations, with students mapped to the correct location?
For example given these students data:
Student Row Column
Paul 1 1
Chris 1 3
James 2 2
Dwayne 3 3
How to have a query output like this:
Student Row Column
Paul 1 1
NULL 1 2
Chris 1 3
NULL 2 1
James 2 2
NULL 2 3
NULL 3 1
NULL 3 2
Dwayne 3 3
Please help! Thank you very much in advance.
While using PHP, Try mysql_insert_id() for your Code.
See Example here:
http://php.net/manual/en/function.mysql-insert-id.php
Good luck.
First of all, you need to know that Mysql haven't a implicit generator of N numbers of rows, like other RDBMS have, but you can emulate this using something like this:
http://use-the-index-luke.com/blog/2011-07-30/mysql-row-generator#mysql_generator_code
Take a look for study porpuse.
But for a first approach to resolve your problem, you can try this:
SELECT IFNULL((SELECT STUDENT FROM StudentSeatPlan B WHERE B.ROW = TB.ROW_ AND B.COLUMN = TB.COLUMN_),'') AS STUDENT,
TB.ROW_,TB.COLUMN_
FROM (
SELECT 1 ROW_,1 COLUMN_ UNION ALL
SELECT 1,2 UNION ALL
SELECT 1,3 UNION ALL
SELECT 2,1 UNION ALL
SELECT 2,2 UNION ALL
SELECT 2,3 UNION ALL
SELECT 3,1 UNION ALL
SELECT 3,2 UNION ALL
SELECT 3,3) TB
Whatever, it seems like you have a schema problem, something wrong it happens that you need generate data in this form in Mysql, maybe you prefered make it in your app if is the case.
I need to filter a table in mysql but can't get past the beginning.
The table has 2 fields:
ID_house house_feature
1 1
1 2
1 4
1 5
2 1
2 3
2 4
3 1
3 2
3 3
I need to filter this table using the following parameters:
house feature = 1
AND
house feature = 2
AND
house feature = 3
So that I get all houses with the requested feature.
I already tried to create something similar to this:
SELECT *
FROM houses
WHERE
house_feature = 1
AND
house_feature = 2
AND
house_feature = 3
But it doesn't work as I expected.
Is there a way to get this result with MySQL?
It seems that I acn filter the table using only the OR operator but this way I can't get the right result.
Thanks in advance for any help.
tony
You can do so ,by matching the distinct count of features per house ,so the house with exactly these 3 features will be returned
SELECT *
FROM t
WHERE
house_feature IN(1 ,2,3)
group by ID_house
having count(distinct house_feature) = 3
Demo
Maybe it's because I don't understand how to search for the right verbiage, but I'm having difficulty understanding how to attach multiple users to a table with multiple columns.
Here is what I'm attempting to do:
table name: user
user_id user_name
1 abc
2 xyz
3 pqr
4 new
table2 name : brackets
id user_id bracket_name
1 4,2 bracket_1
2 4,3,1 bracket_2
3 2,1 bracket_3
4 3,4,2 bracket_4
-- OR --
table name: user
user_id user_name brackets_id
1 abc 2,3
2 xyz 1,3,4
3 pqr 2,4
4 new 1,2,4
table2 name : brackets
brackets_id user_id bracket_name
1 4,2 bracket_1
2 4,3,1 bracket_2
3 2,1 bracket_3
4 3,4,2 bracket_4
I'm using nodejs and sequalize as my ORM and understand enough to read, write, delete and update to these tables, but when it comes to organizing my data, I'm completely lost!
Is it possible to add an array to MYSQL with the user ID's or the brackets that the user is allowed to access? The bracket are generated by a user and then they can invite their friends to join a bracket. Users can join multiple brackets and join other brackets as users.
Any guidance would be very helpful!
I think a Junction Table would simplify this for you: http://en.wikipedia.org/wiki/Junction_table
It would look something like:
table name: user
user_id user_name
1 abc
2 xyz
3 pqr
4 new
table2 name : brackets
brackets_id bracket_name
1 bracket_1
2 bracket_2
3 bracket_3
4 bracket_4
table3 your junction table:
user_id brackets_id
1 2
1 3
2 1
2 3
2 4
etc.etc.
I have table like this:
id products
------ ----------
5 1,2,3
6 2,4,5
9 1,4,7
17 4,6,7
18 1,6,8
19 2,3,6
I have to select only that rows, which row's products column contains one of (2,3) values.
In this case query must return:
id products
------ ----------
5 1,2,3
6 2,4,5
19 2,3,6
But I don't understand how to make construction of this query.
Any ideas?
Thanks in advance.
SELECT id,products
FROM yourTable
WHERE FIND_IN_SET('2',products)>0
OR FIND_IN_SET('3',products)>0
sqlFiddle
Would you mind to try this one please?
select * from TABLE_NAME where products regexp "(^|,)[23](,|$)";
Its doing either two or three at the begining, or at end. Or in between the commas.
Never, never, never store multiple values in one column.
Like you see now this will only give you headaches. Normalize your table. Then you can select normally.
Your table should look like this
id product
-- -------
5 1
5 2
5 3
6 2
6 4
6 5
...
With that table structure your select would be
select id
from your_normalized_table
where product in (2,3)
group by id
having count(distinct product) = 2
That query can make use of indexes and is really fast.